1. Technical Field
This invention relates generally to interfacing systems for portable electronic devices, and more particularly to an apparatus for providing a power and communications interface between a portable electronic device, selected from a variety of such devices, to a common base unit.
2. Background Art
Electronic devices are being developed today at a dizzying rate. Everywhere you look, people are carrying cellular phones, compact disc (CD) players, personal digital assistants (PDAs), pagers, radios, MP3 players, and laptop computers. This proliferation of electronic devices is especially true in the case of cellular telephones. According to the Cellular Telecommunications Industry Association (CTIA), cellular telephone usage in the United States increased 27% between 1999 and 2000. As of December 2000, there were over 109 million cellular subscribers in the United States alone.
There are two problems with this proliferation of electronic devices, however: First, they seem to all use different power supplies with different connectors. Nothing is more frustrating than packing for a trip and having to leave your swimming suit at home because your suitcase is full with four different power supplies for your computer, PDA, phone and CD player.
There is a reason for the various power supplies and connectors. Each host device has different power requirements. For example, a laptop computer consumes much more energy than does a cellular phone. The extra power is needed to run motors like disk drives and CD-ROM players that the phone does not have. Additionally, the laptop may have to illuminate a 120 square inch screen continuously, while the cellular phone need only light a 4 square inch screen occasionally.
Another reason for the differing power supplies are the batteries associated with each device. Different rechargeable batteries have differing charging requirements. For example, a nickel-metal hydride battery may charge to a termination of 6 volts, while a single-cell Lithium-Ion battery can only be charged to 4.2 volts. If the lithium battery were charged with a nickel charger, the lithium battery could become “overcharged” when the voltage exceeded 4.2 volts. Under these conditions, the reliability of lithium cells can be compromised.
The second problem is that as the sophistication of electronic devices increases, data ports to and from the electronic devices are required to transmit data for remote antenna connections, voice and data communications, and most importantly, what is known as “hands free” operation. These functions generally require a physical connection between the phone unit and parts or devices found in a vehicle or accessory. These data ports are typically seem to be manufacturer specific—each manufacturer has it's own unique connector.
The two problems are essentially the same: every portable device has a unique connector for power and data. Designing a “universal” device to work with a plurality of devices is thus problematic.
One solution to the “multiple-device, multiple-accessory” problem is the multi-connector. Referring to FIG. 1, illustrated therein is a multi-prong adaptor 5 commonly available at electronics stores. Such an adapter 5 generally has several different prongs 1,2,3 coupled in parallel to a power cord 4. The power cord 4 may thus be connected to three different types of connectors. The problem with such a device is that the power delivered by the supply is the same no matter what connection you are using. If the power supply is a 6-volt supply, you still cannot charge a single-cell lithium battery with this connector (even if it does fit) because the battery performance may be compromised. Additionally, these connectors generally have no provisions for data communication.
Another possible solution made specifically for cellular phones is the car kit. Cellular phone manufacturers have made available car kits to provide both charging and data communication, as well as hands-free operation. These kits include physical hardware to retain the phone in the vehicle including an attachment for establishing an electrical connection to the phone and various types of remote speakers, microphones, power supplies and antenna connections. These kits also include complex electronics modules to provide battery charging, audio amplification and digital communication interface to the phone unit.
The problem with these car kits is that they are device specific. In other words, you cannot use a Nokia accessory with a Motorola phone. As a result, car kits do not provide any form of universal connection and are neither physically nor electrically interchangeable. Additionally, device specific car kits can be expensive, with costs of the accessory rivaling the cost of the phone itself.
This situation has caused a hardship on cellular telephone users and affected the marketplace for new equipment. Fleet users, for example, cannot provide a universal car kit connection for the variety of phones they may acquire. Users are forced to abandon their investment in the car kit when purchasing new models of telephones. These limitations have prevented businesses such as car rental agencies from providing users with means to use their car phones in rented vehicles. Further, the high cost of these car kits has caused many users to operate hand-held units while driving, an unsafe condition which is subject to increasing governmental concern and regulation.
There is thus a need for an improved interface system capable of coupling to and identifying a plurality of portable electronic devices.